I had the opportunity to watch a friend of mine reload a few weeks ago. There were 3 of us; the friend who was doing the reloading, another friend that reloads as well but was only watching and I. I don't reload but my friend loves to do it for a stress reliever. For a 12 pack and the cost of components, he reloads about a 1000 rounds for me. I have never had a problem with his reloads or how he does it. This time he used a different powder since his supplier was out of his usual stuff. He cross referenced a Lee reloading manual, a Lyman manual and the powder manufacturer load data. They all had different loads and different OALs for the same powder and bullet configuration. I asked, "which one do you use when they are all different?" I received 2 different responses, the friend reloading said he always defers to the powder manufacturer load data. The friend watching disagreed with his choice and said use the Lyman manual because based on the powder powder data, the pressures were too high due to the higher OAL.

Color me nervous to fire the reloads but I trust my friend. We went to the range together and all went fine as usual. The debate is still open between my 2 friends, so is there one source that is a better choice over another or is it up to the reloader?
Just for background this is what my friend loaded:
9mm 115gr zero FMJ bullet
Accurate Arms #5 powder 5.8gr
CCI #500 small pistol primers
Mixed brass but mostly WWB
OAL 1.100
Manual Load- Lee:
9mm 115gr FMJ bullet
Accurate Arms #5 powder 6.4-7.0
OAL 1.095
Manual Load- Lyman
9mm 115gr FMJ bullet
Accurate Arms #5 powder 5.5-7.0gr
OAL 1.090